This application claims the priority of German Application No. 100 37 576.6, filed Aug. 2, 2000, the disclosure of which is expressly incorporated by reference herein.
The invention relates to an electronic control unit and method for the automatic activation of a parking brake in a motor vehicle.
From German patent document DE 196 25 019 A1, for example, an electronic control unit is known in the form of a transmission control device, which in addition to other vehicle functions is used for automatically activating a parking brake in a vehicle. The parking brake is automatically activated independent of at least one specified operating mode of the motor vehicle, which is started with a mechanical ignition key. Such an operating state can include, e.g., falling short of a certain vehicle speed threshold, the position of the ignition key in the lock, and/or the state of the vehicle door (open/closed). At the latest, upon removing the ignition key from the lock, however, the parking brake is activated.
In the future, key-less access and/or driving authorization systems will be used increasingly in order to start motor vehicles. Such a system is known, for example, from the electronic authorization verification device from German Patent documents DE 198 01 064 A1 and DE 198 23 707 A1. Here, wireless code transmission takes place to establish the access and driving authorization. A mechanical ignition key is only provided as a redundant feature. The vehicle is then started and turned off with a rotary switch with simultaneous verification of the authorization through the authorization verification device. After shutting the vehicle off, no mechanical key, therefore, has to be pulled out of the ignition.
Nevertheless, automatic activation of a parking brake with a removed key, wherein an electronic authorization verification device should be considered equal to a conventional key system from a functional point of view, is required by law in some countries. For safety reasons, on vehicles without mechanical keys, the parking brake is therefore automatically activated independently of a key position in dependence of at least one other operating parameter or operating state. Operating parameters or signals that indicate the user has left the vehicle in particular are evaluated, such as an open driver""s door (can be interrogated with a switch in the door) or an empty driver""s seat (can be recognized with seat occupation sensors).
The goal of the invention is to define an optimal operating mode at which the parking brake is activated automatically.
This goal is achieved by an electronic control unit and method for automatically activating a parking brake in dependence of at least one specified operating parameter or operating mode of a motor vehicle, which can be started without a mechanical key. The operating mode for a basic automatic activation of the parking lock is the fact that the internal combustion engine is being shut off. Beneficial embodiments of the invention are the objects of the dependent patent claims.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.